1. Field of the Invention
This invention relates to a device for assembling a synchronizer for a change-speed gear, comprising a hub with a sliding sleeve and at least one cone clutch with a double bevel ring, which is freely rotatable with respect to the hub, between an inner friction ring connectable with the hub and an outer synchronizer ring axially movable with respect to the friction ring by the sliding sleeve, where there are provided mounting stops for the outer synchronizer ring, which are axially fixed with respect to the hub and distributed over the periphery thereof, and a mounting stamp for axially loading the inner friction ring of the cone clutch.
2. Description of the Prior Art
To ensure that in the case of change-speed gears with a hub fixedly mounted on a shaft and a gearwheel freely rotatable on the shaft, the hub can easily be connected with the gear-wheel via a dog clutch, which is formed by a sliding sleeve axially movable on the hub and adapted to be pushed onto a collar on the side of the gearwheel, the gearwheel must take on the rotational speed of the hub. This is achieved by a cone clutch provided between the hub and the gearwheel, which has a double bevel ring effecting a rotational entrainment of the gearwheel, which double bevel ring can be frictionally clamped between an inner friction ring fixedly connected with the hub and a synchronizer ring axially movable with respect to this friction ring by the sliding sleeve. When the sliding sleeve is moved on the hub in the sense of a clutch engagement, the axial entrainment of the synchronizer ring effects an acceleration of the double bevel ring frictionally clamped between the inner friction ring and the outer synchronizer ring, and thus of the gearwheel fixedly connected with the synchronizer ring to the rotational speed of the hub, which provides for the subsequent unimpeded clutch engagement between the sliding sleeve and the collar of the gearwheel. For a rather backlash-free actuation of the cone clutch via the sliding sleeve it is necessary that the axial clearance required for the free running of the double bevel ring be kept as small as possible. For this purpose it is known from U.S. Pat. No. 5,613,289 to define this axial clearance by means of hub-side mounting stops for the synchronizer ring. Provided that the synchronizer ring, the double bevel ring and the inner friction ring engage in each other without any clearance, it is thus possible in the stop position of the synchronizer ring to define the axial position of the inner friction ring on the hub for the clearance determined by this mounting stop. However, the axial frictional forces occurring during the assembly of the synchronizer and the elastic bending behavior of the individual parts of the cone clutch in axial direction must be taken into account during the axial fixation of the inner friction ring on the hub. For this reason, the cone clutch is urged under a bias against the hub-side mounting stops by means of a mounting stamp with a predetermined axial force, where by means of the substantially frictionless movability of the inner friction ring on the hub it is ensured that the bias acting on the cone clutch is indeed determined only by the applied axial force and is not influenced by the axial friction forces between the inner friction ring and the hub, as this would for instance be the case when pressing the inner friction ring onto the hub. For the axial fixation of the friction ring on the hub there is advantageously used a fastening ring, which in the warm condition is mounted on the hub with a radial clearance and is then cooled so as to achieve a shrink fit. Via this fastening ring, the mounting stamp can thus also press onto the inner friction ring, until the warm fastening ring has cooled sufficiently for a corresponding shrink fit.
The bias of the cone clutch during the assembly of the synchronizer in addition provides for checking the assembly, when after the axial fixation of the inner friction ring on the hub the synchronizer ring is rotated before the removal of the mounting stop, with the external axial force having been eliminated, and the torque required for the rotation is determined as a measure for the actual bias of the cone clutch. Although by means of this known assembly method very close tolerances can be maintained even under the conditions of a mass production, the easy practicability of this method depends on whether the axial bias of the cone clutch can be applied via the fastening ring without any major frictional forces between the hub and the fastening ring, which excludes for instance a press fit of the fastening ring on the hub.